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October 19, 2023
Last updated

How to Brew an Imperial Oatmeal Stout: Homebrew Beer Recipe

Chief Operating Officer at Clawhammer

Imperial Oatmeal Stout RECIPE KIT

The recipe kit makes brewing this beer at home simple. Follow along with the steps in this article and enjoy an amazing beer in a few weeks.

Click here to buy our ingredient kit

Imperial Oatmeal Stout


  • 64.7% Pale Malt
  • 10.8% Flaked Oats
  • 8.6% Chocolate Malt
  • 8.6% Crystal 60
  • 5.4% Roasted Barley
  • 1.9% Carafa II

All of the grains in the recipe kit come double crushed in our kit

How to Make Imperial Oatmeal Stout Beer

  • Make sure the ball valve on the kettle is closed before adding water
  • Add 7.75 gallons of water to the brewing kettle if brewing on the 120v system OR Add 8 gallons of water to the brewing kettle if brewing on the 240v system
  • Add the grain basket to the kettle
putting in grain basket
  • Put the lid on the kettle (this helps speed up the heating process)
  • Set the controller to 154F 
  • Once the water is at 154F remove the lid
  • Slowly add the grains to the grain basket in the kettle.

stirring mash

It's important to stir your mash to break up any clumps (doughballs)

 Attach the Hoses

  • Attach a hose from the output of the kettle to the input of the pump
  • Attach a 2nd hose from the output of the pump to the spray valve on the lid of the kettle. The output of the pump has the ball valve attached to it.
  • In order to purge the air out of the lines simply disconnect the hose from the spray valve and hold the hose so it is pointing at the grains in the basket. Then open the ball valve on the kettle and press the pump button on the controller to turn on the pump. Once the air is out of the lines and wort is flowing freely turn off the pump,  reattach the hose to the spray valve and turn the pump back on. This sounds like a lot of steps but it only takes a few seconds.


  • Set a 60 minute timer on the phone. Let the wort recirculate for 60 minutes and the controller will maintain the mash temperature of 154F. 
  • Optional: Once the 60 minute mash is finished set the controller to 170F for a mash out. Continue to recirculate for another 10 minutes once the kettle is at 170F.
  • Once the 60 minute mash or the optional mashout is complete remove the grain basket. Lift the grain basket and set it on the 3 hooks. A pully or a friend makes lifting the grain basket easier.
  • Let the sweet wort from the grain basket drip into the kettle for about 5-10 minutes. Use a plate or lid to a sauce pan to press down on the grains to extract more liquid from the grains. This also speeds up the draining process.
  • At this time either remove the hoses or leave them connected.  If removing the hoses use a clean brewing bucket to keep from making a mess when disconnecting the hoses. The wort can be saved and added back the kettle or poured  down a drain. Heat tolerant gloves are highly recommended as the hoses and fittings will be hot. The hoses can also be left attached - just move onto the next step.
  • Switch the controller to manual mode and set it to 100% of power if brewing on the 120v system. If brewing on the 240v system set the controller to 100% of power until it start boiling and then drop it down to around 55% of power. For detailed directions on switching the controller to manual mode click here
  • Add the hop basket to the kettle. Make sure the hops basket is not sitting on the heating element.
  • If brewing with the 120v system place the lid on the kettle. The hop basket creates a gap which allows the steam to escape. The lid is necessary on the 120v system to create a vigorous boil. Keep the controller at 100% of power for the entire boil.
  • If brewing on the 240v system leave the lid off during the boil. Set the controller to 100% of power and once it is at a boil drop the percent down to around 55%. Adjust the % of power for boil preference. 
  • This beer only requires a 30 minute boil. Once the kettle is up to a boil start a 30 minute timer (phones work great)

Hop Additions

  • At the Start of the 30 minute boil
    • Add 2 ounces Magnum to the hop basket
  • With 15 minutes left in the boil 
    • Add 2 ounces Fuggle to the hop basket
    • Whirlfloc tablet to the kettle
boiling wort

Hops added to the hop basket

Hoses and Chilling

  • When the 30 minute boil is finished press the heat button on the controller to turn off the heat.
  • Attach one end of the garden hose to the water source and attach the other end to water IN on the plate chiller.
  • Attach a 2nd hose to the water OUT on the plate chiller and run it down the drain or to a garden. (this is clean waste water)
  • First Brewing Hose: Attach one end of this hose to the ball valve on the kettle and the other end to the pump IN on the pump.
  • 2nd Brewing Hose: Attach one end of this hose to the pump OUT on the pump and attach the other end to wort IN on the plate chiller.  (The pump out has the ball valve attached to it)
  •  3rd Brewing Hose: Attach one end of the hose to wort OUT on the plate chiller and insert the other end of the hose into the kettle. Use the clamp to hold the hose in the kettle. 
  • Turn on the cooling water and check for leaks. If any water is leaking tighten up the garden hose connections on the plate chiller.
  • Turn on the pump. This will recirculate the hot wort through the plate chiller 
  • Once the entire brewing kettle is chilled down to around 65-67F turn off the cooling water.
  • Press the pump button on the controller to turn off the pump. Unclamp the hose and move it from the kettle to the fermenter.
  • Once the hose is securely inside the fermenter press the pump button to turn the pump back on. This will transfer the cooled wort from the kettle into the fermenter. 
  • Once the kettle is almost empty tip the kettle towards the front in order to get all of the sweet wort into the fermenter. 

Yeast and Fermentation

  • Sprinkle 2 packet2 of US04 yeast on top of wort in the fermenter. Ferment  at room temperature (65-68) for 2 weeks.


pitched yeast on top of wort

Sprinkle yeast on top of wort


  • Starting gravity 1.075
  • Final Gravity 1.14
  • ABV  8% 


It's a great beer. Deep black color and a rich, creamy head. The aroma will is full of roasted coffee, chocolate, and caramel notes. The flavor is complex and malty, with a hint of sweetness and a smooth, creamy mouthfeel.

"This goes down pretty easy, it doesn't taste like it's 8+%."

Brew Day Video

Emmet Leahy is the Chief Operating Officer and lead product developer at Clawhammer Supply, a small scale distillation and brewing equipment company. He loves the process of developing new equipment for making beer at home just as much as he does using it to brew his own beer. He's also passionate about teaching people how to use distillation equipment to produce distilled water, essential oils, and with the proper permits, fuel alcohol and distilled spirits.

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